When Rafael Nadal begins his clay-court season at the Rolex Monte Carlo Masters on Wednesday, he will do so with a few doubts hanging in the air about his fitness, namely whether his ailing knees will be ready for the rigors of the red stuff.

After pulling out of the BNP Paribas Open in Indian Wells last month because of a right knee issue before a much-anticipated semifinal against Roger Federer, Nadal took two weeks off to recover and get his body in shape.

With Nadal out of action between last year's US Open and this year's Australian Open with knee trouble, an abdominal injury and then an ankle issue that required surgery, the stop-start nature of his past 18 months has left some wondering if this year's clay-court season could be more open than usual.

Editor's Picks

And yet, this week Nadal is going for a record 12th title in Monte Carlo, and everyone from Novak Djokovic to Dominic Thiem makes him the overwhelming favorite to open the season in familiar style.

Nadal arrived in Monte Carlo on Friday and has looked good in practice and appeared relaxed in his media commitments away from the court -- usually a good sign of his state of mind. At an event he has dominated, winning each of the past three years, he is instantly at ease.

That feeling should help him for the start of yet another comeback, a situation he has been in many times before, and one from which he has usually regained top form, fast.

As he discussed his hopes for the next couple of months at the Monte Carlo Country Club on Monday, Nadal admitted it had been "a tough year and a half," an inability to play more than a couple of weeks in a row costing him momentum on several occasions.

But this is Nadal, and this is clay, a surface on which he has been as dominant as anyone in history. Eleven times the champion in Monte Carlo, he also will be going for title No. 12 in Barcelona next week and title No. 12 in the French Open at Roland-Garros next month -- numbers that hardly seem possible, especially when said out loud.

What has kept him confident, though, is that when he has played, he has played well. He made the semifinals of the US Open last September and then looked superb in Melbourne in January before being routed by Djokovic in the final of the Australian Open.

"It's true that there are a lot of issues that happened in the last year and a half that could be a moment to be a little bit frustrated, but being honest, every time I've had the chance to be back, I competed," Nadal said.

"I started [practicing] two weeks ago and, yes, my knee is good, so, happy for that," he added. "Now I need to work on the tennis. That's the goal. I arrived here on Friday as usual, I had some hours of practice and I hope the competition puts me in the rhythm that I need."

World No. 1 Djokovic, twice a winner in Monte Carlo, is seeded to potentially face Nadal in the final, while Thiem, the runner-up to Nadal at last year's French Open, and Alexander Zverev, the German who won in Rome two years ago and finished as runner-up to Nadal last spring, will also be contenders.

Nadal will play fellow Spaniard Roberto Bautista Agut in his first match, a tricky opener, but if he gets through that, the chances are he will roll into form sooner rather than later. He plans to play in Barcelona, Madrid and Rome, as usual, before defending his French Open title, and few would bet against him dominating once again.

"In these tournaments, you must always put Rafa at No. 1," Craig O'Shannessy, an analyst for the ATP Tour, told the ATP Tennis Radio podcast this week. "Somebody must take him out of the draw. As soon as he's taken out of the draw, then we can start talking about everybody else. All conversations start with Rafa -- everybody else is a dark horse."

There is a long way to go before Paris, of course, and Nadal will not get ahead of himself.

"Now it's about working every day, trying to make small improvements in every practice, because I had to stop after Indian Wells for a while again and start slow, so it's always like a comeback," he said.

"It's important for me to have good practice [Tuesday] before the tournament starts and to be competitive for the first round -- it's going to be a tough one. Let's see."